Tumor infiltrating lymphocytes are currently under investigation in Surgery Branch clinical protocols for the adoptive immunotherapy of patients with advanced cancers. Responses to therapy have been observed in select patients with melanoma. In vitro studies have shown that melanoma TIL are T cells which can specifically recognize autologous tumor. Identifying tumor Ag and mechanisms by which TIL destroy tumor is essential to optimizing current clinical protocols and devising new therapeutic strategies. Areas of study are: 1. Melanoma-specific Ag recognized by CD8+ T cells. We have found that some melanoma Ag are commonly expressed in the patient population. CD8+ T cells which specifically recognize autologous melanoma Ag can also respond to allogeneic HLA-matched melanoma cells sharing the same Ag, by cytolysis and/or cytokine secretion. Transfection of the HLA-A2.1 gene into HLA-mismatched melanomas has shown that they can also share melanoma Ag recognized by HLA-A2 restricted T cells. These Ag appear to be present on certain other neural crest derived tumors as well. 2. Other tumors specifically recognized by human T cells. The function of cytokine secretion (TNF-alpha, IFN-ga,,a, GM-CSF) has been used to monitor CD4+ and CD8+ TIL recognition of tumor Ag. TIL derived from 4 of 10 colon carcinomas, 2 of 12 lymphomas, and 3 of 11 breast carcinomas specifically secreted cytokines in response to autologous and/or HLA-matched allogeneic tumors. In some cases, CD4+ T cells were solely responsible for the observed response. 3. Function of human B cells in tumor Ag presentation. We have identified an EBV-transformed B cell line capable of processing and presenting melanoma Ag to autologous CD4+ T cells. Studies are in progress to identify the tumor-derived peptide recognized in this system, using immunoaffinity chromatography to isolate MHC II-peptide complexes.